Add VersionMismatch error variant and check_version() helper to erp-core.
All 13 mutable entities now enforce version checking on update/delete:
- erp-auth: user, role, organization, department, position
- erp-config: dictionary, dictionary_item, menu, setting, numbering_rule
- erp-workflow: process_definition, process_instance, task
- erp-message: message, message_subscription
Update DTOs to expose version in responses and require version in update
requests. HTTP 409 Conflict returned on version mismatch.
- Collapse nested if-let in user_service.rs search filter
- Suppress dead_code warning on ApiDoc struct
- Refactor server routing: nest all routes under /api/v1 prefix
- Simplify health check route path
- Improve workflow ProcessDesigner with edit mode and loading states
- Update workflow pages with enhanced UX
- Add Phase 2 implementation plan document
